/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.client.reactive;


import java.nio.ByteBuffer;
import java.util.concurrent.Executor;

import org.eclipse.jetty.io.ByteBufferPool;
import org.eclipse.jetty.io.MappedByteBufferPool;
import org.eclipse.jetty.util.ProcessorUtils;
import org.eclipse.jetty.util.component.LifeCycle;
import org.eclipse.jetty.util.thread.QueuedThreadPool;
import org.eclipse.jetty.util.thread.ScheduledExecutorScheduler;
import org.eclipse.jetty.util.thread.Scheduler;
import org.eclipse.jetty.util.thread.ThreadPool;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * Factory to manage Jetty resources, i.e. {@link Executor}, {@link ByteBufferPool} and
 * {@link Scheduler}, within the lifecycle of a Spring {@code ApplicationContext}.
 *
 * <p>This factory implements {@link InitializingBean} and {@link DisposableBean}
 * and is expected typically to be declared as a Spring-managed bean.
 *
 * @author Sebastien Deleuze
 * @since 5.1
 */
public class JettyResourceFactory implements InitializingBean, DisposableBean {

    @Nullable
    private Executor executor;

    @Nullable
    private ByteBufferPool byteBufferPool;

    @Nullable
    private Scheduler scheduler;

    private String threadPrefix = "jetty-http";


    /**
     * Configure the {@link Executor} to use.
     * <p>By default, initialized with a {@link QueuedThreadPool}.
     *
     * @param executor the executor to use
     */
    public void setExecutor(@Nullable Executor executor) {
        this.executor = executor;
    }

    /**
     * Configure the {@link ByteBufferPool} to use.
     * <p>By default, initialized with a {@link MappedByteBufferPool}.
     *
     * @param byteBufferPool the {@link ByteBuffer} pool to use
     */
    public void setByteBufferPool(@Nullable ByteBufferPool byteBufferPool) {
        this.byteBufferPool = byteBufferPool;
    }

    /**
     * Configure the {@link Scheduler} to use.
     * <p>By default, initialized with a {@link ScheduledExecutorScheduler}.
     *
     * @param scheduler the {@link Scheduler} to use
     */
    public void setScheduler(@Nullable Scheduler scheduler) {
        this.scheduler = scheduler;
    }

    /**
     * Configure the thread prefix to initialize {@link QueuedThreadPool} executor with. This
     * is used only when a {@link Executor} instance isn't
     * {@link #setExecutor(Executor) provided}.
     * <p>By default set to "jetty-http".
     *
     * @param threadPrefix the thread prefix to use
     */
    public void setThreadPrefix(String threadPrefix) {
        Assert.notNull(threadPrefix, "Thread prefix is required");
        this.threadPrefix = threadPrefix;
    }

    /**
     * Return the configured {@link Executor}.
     */
    @Nullable
    public Executor getExecutor() {
        return this.executor;
    }

    /**
     * Return the configured {@link ByteBufferPool}.
     */
    @Nullable
    public ByteBufferPool getByteBufferPool() {
        return this.byteBufferPool;
    }

    /**
     * Return the configured {@link Scheduler}.
     */
    @Nullable
    public Scheduler getScheduler() {
        return this.scheduler;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        String name = this.threadPrefix + "@" + Integer.toHexString(hashCode());
        if (this.executor == null) {
            QueuedThreadPool threadPool = new QueuedThreadPool();
            threadPool.setName(name);
            this.executor = threadPool;
        }
        if (this.byteBufferPool == null) {
            this.byteBufferPool = new MappedByteBufferPool(2048,
                    this.executor instanceof ThreadPool.SizedThreadPool
                            ? ((ThreadPool.SizedThreadPool) executor).getMaxThreads() / 2
                            : ProcessorUtils.availableProcessors() * 2);
        }
        if (this.scheduler == null) {
            this.scheduler = new ScheduledExecutorScheduler(name + "-scheduler", false);
        }

        if (this.executor instanceof LifeCycle) {
            ((LifeCycle) this.executor).start();
        }
        this.scheduler.start();
    }

    @Override
    public void destroy() throws Exception {
        try {
            if (this.executor instanceof LifeCycle) {
                ((LifeCycle) this.executor).stop();
            }
        } catch (Throwable ex) {
            // ignore
        }
        try {
            if (this.scheduler != null) {
                this.scheduler.stop();
            }
        } catch (Throwable ex) {
            // ignore
        }
    }

}
